Method of and means for attaching electrical conductors to brushes



Jan. 20, 192-5; 3 1,523,599

A. LINDBLADE METHOD OF AND MEANS FOR ATTACHING ELECTRICAL CONDUCTORS TO BRUSHES Filed July 15, 1921 //v ENTOR m l W ATTORNEY was Jan.20,1925. I 1,523,599

UNITED STATES- PATENT OFFICE.

AB'I'HUR.LINDBLADE, F BRADFORD, PENNSYLVANIA, ASSIGNOB Tp CORLISS CAB- BON COMPANY, INCORPORATED, OF BRADFORD, PENNSYLVANIA, A CORPORATION I OF PENNSYLVANIA.

IETEOD OF AND MEANS FOR ATTAOEING ELECTRICAL CONDUC'IORS TO BRUSHES.

' Application filed July 15, 1921. Serial No. 484,548.

To all whom it may concern: terial which will spread laterally when com- Be it known that I, ARTHUR LINDBLADE, pressive force is ap lied thereto longitudia citizen of the United States, residing in nally, i. e., in the direction of the axis of 50 Bradford, county of McKean, and State of the opening. The material will naturally I Pennsylvania, have invented certain new yield most readily at points at which there and useful Improvements in Methods of and are crevices between itself and the cable Means for Attaching ElectricalConductors and between the cable and the walls of the to Brushes, of which the following is a opening. The cable therefore will'be caused 55 specification. to shape itself accurately to the walls of This invention relates to methods of and the openin and the said material will means for securing electrical conductors of adapt itself 0 the interior of the cable, and the type commonly called pig tails to fill all crevices therein. The net result brushes of the character ordinanly employtherefore, of this process is .to produce a 60 ed for delivering electric currents to, or substantially solid plug consisting of the 5, collectin the same from, the rotating eleend of the cable completely filled with the ments of dynamo-electric machinery. material, the exterior shape of this plug The present invention proposes an imbeing the same as the shape of the opening. provement on the form of pig tail connec To enhance the mechanical security of the 65 tions in which the pig tail or cable is seconnection the walls of the opening are refcured in an opening in the brush b means of erably provided with recesses into whic the -a member inserted 1n the interioro the cable. strands of the cable will be forced, thus 'l his interior member in the prior art ordiincidentall increasing the actual area of narily consisted of a device actin inthe contact. The present invention thus not manner of an expansion bolt to orce the only renders it possible to obtain a large conductors of the cable against the walls of area of actual contact and low contact rethe opening. The devices of this characsistance without the employment of excester are composed of hard, unyieldin ma sive force, but it provides for enhanced terial such as ordinary copper or brass, mechanical security without the loss of area 18 which by pure outward ressure, is intendof contact.

a. ed to bring about the esired mechanical A good understanding of the invention security and low resistance of contact. It may now be had from the following dewill be readil understood, however, that scription of one manner of practicin the unless the we] 5 of the opening in the brush same, and one, form of embodiment t ere- O0 and the pig tail itself are very smooth so as to of, reference bein had to the accompany- :5 conform closely, there will be contact only in drawing, in w ich,

at certain high spots, and the true area of Tigure 1 illustrates the manner in which contact will be considerably less than the the connection is made; total available area. With smooth walls, on Figure 2 shows. one form ofinsert for SI the other hand, the mechanical security will use in this invention; and I 40 be comparatively low, as the pig tail may be Figure 3 illustrates the finished connecreadily pulled out unless an extraordinarily tion. large interior pressureis em loyed. This Similar characters of reference designate pressure, however, is limited ause of the similar parts in each of the several views. 00 tendency of the brushes to fracture under In accordance with the present invention,

too high a strain. the brush B is provided with an opening To obviate these difliculties the resent such as 1, slightly larger than the diameter invention proposes the employment 0 a maof the pig tai 2 which is to be secured to the brush. The side walls of opening 1 are preferably provided with annular recesses such as 3 for the purpose of enhancing the security of the mechanical connection, as will beexplained hereinafter.

The pig tail, which is preferably in the form of a stranded cable, is introduced into opening 1, so'that the ends of the conductors thereof engage the bottom Wall of the opening, At a oint just above the opening the cable is'slig tly opened or twistad apart so that'a plug 4 may be inserted into the interior of the cable.

This plug is preferably slightly pointed as shown and made up preferably of a composition consisting of'about 80 per cent copper, 15 per cent lead and 5 per cent graphite, these materials being combined into a solid composition by any suitable process, as for example, by mixing the materials in powder form, the copper being preferably approximately 200 mesh and the lead having a substantially equal or even greater fineness. This mixture is compressed indies of suitable form under a pressure of several tons per square inch--' suflicient to cause the material to hold firm 1y together. These pieces are baked in a reducing; atmosphere until a temperature of approximately 1500 F. 'has been attained. The material thus produced is solid inform, has good mechanical strength, low electrical resistance and possesses such mal: leability as to flow or yield laterally when subjected to compressive force, partlcularly hammering by hand or by an automatic device such as the well known oscillatory punch. Such a device applies the blows comparatively lightly and in rapid succes-- ion, thus saving time and minimizing-any tendency of crackingor other breach of continuity of the material-of which the member 4 is composed. I

The plug is then hammered downwardly toward'the bottom of the opening, this op eration being continueduntil the material of the plug yields to the compressive forces and flows laterally to enter the crevices of the cable, forcing the strands thereof into ,intimate engagement with the walls of the opening, and causing, the same to enter the recesses 3. The end offthe cable and the member 4 are thus united into a substantially solid plug devoid of internal crevices and having therefore hi h electrical conductivity. The shape of the plug, moreover, conforms'to the shape of t e opening, so

that there is a large area of contact and low contact resistance, as well as mechanical security. j 7

Although the material with which the interior of the cable is filled is described as consisting preferably of a solid plug of malleable material, it will beunderstood that the invention is not limited thereto, and

' that in fact any material may be employed which will yield as above described so as to give the desired result.

Manyother changes and modifications.

.an opening of a brush which consists in in serting the end of the pigtail in the opening, introducing a member of malleable material within the central portion of the pigtail, and subjecting said member to longitudinal compressive force so as to brin about lateral flow of the material of sai member, whereby said pigtail is forced into intimate engagement with'the walls of said opening. 2. The method of securing a stranded cable in an opening of a brush, which consists in recessing the side'of the opening, introducing the 'end of the cable in the opening, and subjecting a member of malleable material in the interior of the cable to longitudinal compressive force to cause its lateral expansion, whereby the strands of said cable are forced into the said recesses and the said member is forced into the interior recesses of the said strands.

3; In combination, a brush provided with the cable, whereby the strands of the cable are compressed against the Walls of said opening and caused to enter the said sidewalls.

4. The methodof securing a conductor in an opening in a brush, which consists in inserting the end of said conductor in the opening, filling the'interior of said conductor with conductive material and subjecting said material to compressive-force, soas to cause the said material to adapt itself to the crevices ofsaid conductor and force the same .into intimate engagement with the wall of the opening of the brush '5. In combination, a'brush provided with an opening having recessed sidewalls, a

recesses conductor cable for said brush, said-cable 7 having one end in said opening, and a plug of metal graphite composition interior to said cable and compressed to retain said cable within said opening.

6; In combination, a brush rovided with an opening havin recessed si ewalls, a'conductor for sald rush, and a'compressed to said conductor for retaining said conductor-in said brush; L Y

7. The method of. securing a. stranded plug of metal graphite composition interior conductor in an opening in a brush,- which consists in inserting the end portion of said conductor into the opening, opening the strands of the conductor at a point above the portion of the conductor inserted within the opening, and introducing a member of malleable conducted material into the interior of the conductor and subjecting said member to compressive force so as to cause the said mem er to adapt itself to the crevices of the said conductor and force the same into intimate enga ement with the Wall of the opening of the rush.

In testimon signature to t whereof I have afiixed my 18 specification.

ARTHUR LIN DBLADE. 

